Thanks again for the reply. The impeller is designed to turn counterclockwise. I turn my wrench on it just now counterclockwise and it does not want to come loose. I don't want to have to take a "Johnson" bar to it or I know something will break. Do I have to remove the impeller in order to replace the water pump?
Thanks. Craig.

Thank you for your reply. Your explanation is excellent. It looks to me that this 12mm (nut) or what looks like a nut is actually part of the impeller casting from what I can see. I have tried with minimal amount of force to remove and my gut instinct tells me it's not coming off. So your explanation makes sense. I'm just wondering how I should go about removing this impeller? Do I just try and pull off? Or turn it in the direction of rotation? I have taken many impellers out of small engines. Usually Polaris Liberty snowmobile engines and they have a separate nut holding the impeller on. So this CFM is different for me for sure. Thx. Craig.

Greetings. I'm new to this forum and have a question? I have an older 2007 500 2 up and have significant coolant in the oil. At first I thought it was the head gasket because compression was 30 psi. Upon further inspection I noticed lots of excess silicone around the water pump. Yep, I believe it is the mechanical seal. Can someone please tell me which way the 12 mm nut comes off the impeller? Clockwise or counterclockwise? I can't seem to locate any info on this year of 500? Thank you very much. Craig in Midland, Ontario